EMPLOYEE WAS CHANGING BUSHINGS IN A CUSHION HITCH ON A 10,000 GALLON WATER WAGON. HE WAS ACCESSING THE WORK WITH 4' TALL STEP STOOL. HE STEPPED BACKWARDS OFF THE STOOL AND FELL TO THE SHOP FLO OR. HE DID NOT WANT MEDICAL ATTENTION AT THE TIME, BUT HIS RIGHT HAND CONTINUED TO BOTHER HIM. ON 1-30-02 HE WAS SEEN BY A PHYSICIAN WITH A DIAGNOSIS OF FRACTURED BONE IN HIS HAND.